New Laser Reveals Substances to Military Aircraft, Uncovering Hidden Dangers

A new laser could help military aircraft identify hidden dangers, such as weapons arsenals, far below them during missions. The new piece of technology can show what objects are made of, which makes it extremely useful for identifying hidden locations.

The laser works by emitting a broadband beam of infrared light. While most lasers emit light of one wavelength, or color, super-continuum lasers like the new one actually give off a tight beam packed with columns of light covering a range of wavelengths and a blend of colors. Because this beam is in the infrared region, though, it's invisible to human eyes. Yet it can reveal vital information to those that can interpret its data.

The infrared light contains what is referred to as the "spectral fingerprinting range." These frequencies can detect echoes of the vibrations of molecules that make up a solid substance. In fact, a substance's spectral fingerprint can reveal which wavelengths of light it absorbed and which it reflected. This, in turn, can reveal exactly what the substance is since different substances absorb and reflect different wavelengths.

"A grey structure looks grey in visible light, but in the infrared, you can see not only the shape, but also what's inside it," said Mohammed Island, a professor of electrical engineering and computer science and biomedical engineering at the University of Michigan, in a news release. "For the defense and intelligence communities, this could add a new set of eyes."

The general concept is that aircraft flying at higher altitudes could use these lasers to illuminate a region with a brightness comparable to sunlight. They could then image this region and learn exactly what's there. In addition, these lasers could improve upon today's full-body airport screening technology. Since the lasers can detect chemical composition, they could be a huge step up for security.

"Those are imaging devices looking for bumps where there shouldn't be bumps," said Islam. "They're looking for shapes that are odd or different. But they can't see the chemicals in the shapes. That's why you have to take your shoes off. But our laser can detect the chemical composition."

The findings are published in the journal Optics Letters.